1. Field of the Invention
The present invention relates to an improvement in a liquid container made of a composite sheet and having a spout attached to the exterior surface of the container body.
2. Background Art
As well known, liquid containers made of a composite sheet comprising a paper layer as the core and resin films laminated on the front and back surfaces of the paper layer are widely used as containers filled with juice, milk, mineral water, alcoholic drink and the like. Spouts of the liquid containers are classified into an exterior type of which a spout is attached to an exterior surface of a liquid container and an interior type of which a spout is inserted from inside a liquid container into a hole in the composite sheet and attached to an interior surface of the liquid container. The exterior type is superior in productivity and on the other hand the interior type is superior in appearance.
There is well known as the exterior type liquid container with a spout a liquid container of Japanese examined utility model application publication SHO.58-37828. In the structure of this liquid container, a sealing film b, as shown in FIG. 2, seals from inside the container body a a circular hole H serving as a spout-attached portion of the container body a. This liquid container involves a problem that since an opening of the sealing film b by means of an opening blade d of a plug c, causes the edge surface of the paper core of the composite sheet defining the hole H in the container body a to contact a liquid content in the liquid container to be swollen the liquid container is degraded in strength and/or deformed.
FIG. 3 shows a liquid container with a spout of Japanese examined utility model application publication SHO.63-18582 for overcoming this problem. In the structure of this liquid container, an annular spout-attached film e having a smaller diameter than the hole H in the container body a is sandwiched between the container body a and the spout c to ensure the attachment of the spout c to the container body a. The spout-attached film e also is bonded to the outer surface of the sealing film b to prevent the edge surface of the paper core of the composite sheet defining the hole H in the container body a from a contact with a liquid content in the liquid container.
These liquid containers are made of a composite sheet the opposite surfaces of which are covered with a polyolefine resin of high heatsealability, for example, polyethylene resin (referred to as PE resin hereinafter). Since PE resin tends to adsorb an aromatic component of an orange juice or the like and oxidation and decomposition of PE resin create a peculiar smell, the odor and the flavor of liquid content tend to be unbalanced.
There are known as resins adsorbing a small quantity of an aromatic component and creating a small quantity of smell polyester resin and ethylene-vinyl alcohol copolymer resin. Since these low-smelly and low-adsorbent resins have a poor heatsealability to polyolefine resin, it is difficult that the prior art sealing film b seals the hole H in the container body a from inside the container body a when the innermost layer of the container body a constituting a liquid-contacting layer is made of one of the low-smelly and low-adsorbent resins.
To overcome this problem, the present applicants proposed a liquid container with a spout in Japanese utility model application HEI.3-6431. FIG. 4 shows this liquid container with the spout. In the structure of this liquid container, the container body a is made of a composite sheet, the composite sheet comprising the core f, an outermost layer g of PE resin on the core f and an innermost layer h of polyester resin (i.e. a low-smelly and low-adsorbent resin) on the core f. A sealing film b is bonded to a portion of the innermost layer h of the container body a surrounding the hole H so that the composite sheet of the container body a and the sealing film b sandwich a connecting film i having a hole with a diameter equal to or slightly larger than that of the hole H. An annular spout-attached film e having a circular hole with a diameter than the hole H is bonded to a part of the outermost layer g surrounding the hole H, to the edge surfaces of the hole H and the hole in the connecting film i, and to a part of the outermost layer of the sealing film b. A spout c is attached to the spout-attached film e.
The connecting film i comprises the core, an outermost layer 1 of polyester resin adjoining the inner-most layer h of the container body a and an innermost layer k of PE resin adjoining the sealing film b. The outermost layer j of the connecting film is heatsealed to the innermost layer h of the container body a with both the outermost layer 1 and the innermost layer h made of polyester resin.
The sealing film b comprises the core, an outermost layer 1 of PE resin adjoining the connecting film i and an innermost layer m of polyester resin. The outermost layer 1 of the sealing film b is heatsealed to the innermost layer k of the connecting film i.
The spout-attached film e comprises the core, an outermost layer n of PE resin (the same resin as the spout c) adjoining the spout c and an innermost layer o of PE resin adjoining the container body a. The spout-attached film e, as described above, extends from the part of the container body a surrounding the hole H to the sealing film b and is heatsealed to the spout c, the container body a, the connecting film i and the sealing film b.
In the structure in which the spout-attached film is attached to the exterior surface of the container body and the connecting film and the sealing film are arranged on the interior surface side of the container body, there may be problems in that since portions of the sealing film and the connecting film frequently contacting a liquid content must be made of a polyolefine resin (e.g. PE resin) these portions tend to adsorb an aromatic component and the smell of the polyolefine resin tends to transfer to the liquid content.
In addition, since the natures of the innermost and outermost layers of the sealing film are different, the sealing film tends to wrinkle during heatsealing of the sealing film and the connecting film. The spout-attached film thus is insufficiently heatsealed to the sealing film which has wrinkled. The heatsealed Joint between the two films tends to cause a pinhole. Therefore, there may be a problem that the liquid content possibly infiltrates the container body after the liquid content is spouted through an opened sealing film and therefore the hole in the container body.